Using a starter, which is usually designed as an electric machine, for example, as a DC machine, to start an internal combustion engine is known. During the startup of an electric machine or an electrical drive, for example, a starter in an internal combustion engine, high starting currents typically occur. Limiting them is an important task in order to minimize the vehicle electrical system voltage drop during the start in the motor vehicle, for example.
A device for controlling the current flow through a starter of an internal combustion engine is described in German Application No. DE 102 52 511 A1. A maximum allowed battery current is calculated therein by a first arithmetic unit. This maximum allowed battery current is provided to a second arithmetic unit, which in turn calculates a maximum allowed starting current in consideration of a prediction of the current consumption of further consumers.
A device for starting an internal combustion engine may be inferred from German Application No. DE 100 21 153 A1, in which a current limiting unit, using which a current flowing to the drive unit is limited to a predetermined amplitude value, is situated in a connection path between the vehicle battery and the drive unit.
An electronic contactor control for regulation of the DC feed in the event of a varying supply voltage by current pulsing and using a freewheeling circuit is described in European Application No. EP 387 729 A2. A freewheeling diode is provided to protect the circuit in the shutdown phases, i.e., in the phases having zero current.
The cited approaches for current pulsing using zero current in the cutoff or shutdown phases require a freewheeling diode to protect the circuit through high induced voltages in the shutdown phases, however.
Furthermore, a method for starting an internal combustion engine using a starter and a starter controller connected thereto is described in European Application No. EP 2 148 084 A2. In this method, a starter current is regulated in a defined way during the starting procedure by the starter controller, which includes electronic components. The starter current is controlled during the starting procedure and is not connected directly to the battery or to an energy store. The starter controller has a current regulating unit, which may in turn include a DC/DC converter.
European Application No. EP 1 041 277 B1 describes a starter regulating device for motor vehicles to prevent wear. Means for reducing the feed voltage at the beginning of the starting procedure are provided for this purpose.
A further option for limiting the current is provided by the temporary connection in series of an additional resistor. The total resistance in the closed circuit is thus increased sufficiently that the flowing current is limited to a defined value.
A starter for starting an internal combustion engine is presented in U.S. Patent Application Publication No. 2004/0168664 A1. In this context, a resistor for limiting a current is described, the current being set in such a way that the starting procedure may take place.
The use of a fixed resistor is disadvantageous because of its overall size and the heat development connected thereto. Since the resistor has a fixed value, it may not be adapted.